In industrial and manufacturing applications, the cleaning or rethreading of bores for acceptance of threaded studs or bolts is often needed. For example, when manufacturing personnel have difficulty getting a bolt to start into a weld nut, the threads inside the nut must be cleaned or recut. The rethreading or the cutting of threads in these bores is a laborious task requiring high torque to cut the threads. In many such situations, a tap is used as the thread cutting tool.
A tap is typically made of hardened steel, with very sharp interengaging teeth. The taps are used with pneumatic guns which have an average gun speed of nine thousand three hundred revolutions per minute. In many cases, the tap is being used in an area of tight tolerance, where visual feedback is difficult or impossible. Hence, the operator or assembler must have tactile feedback to confirm that the tap is properly situated. Obviously, when a hand or glove comes into contact with the teeth on the tap, particularly if the teeth portion is rotating, the result can be minor to severe injury to the operator.
It is seen then that there exists a need for a safety feature that can minimize or prevent injury to the operator of a toothed or threaded cutting tool.